High performance multi-functional trilayer membranes as permselective separators for lithium-sulfur batteries

Multi-walled carbon nanotubes (MWCNTs) and magnesium aluminate (MgAl2O4) were coated on either side of a commercially available Celgard 2320 membrane by a simple doctor blade method. This trilayer membrane (TLM) was subjected to ionic conductivity, thermal stability and contact angle measurements. Each layer of the TLM functions for a specific purpose: the MWCNTs provide electronic conductivity while the pores of the Celgard 2320 membrane facilitate lithium-ion transport and MgAl2O4 suppresses the shuttling of polysulfides due to the electrostatic attractive force. The TLM exhibited superior thermal stability and ionic conductivity than the uncoated Celgard 2320 membrane. The Li-S cell with a TLM offered a higher discharge capacity than the one with an uncoated membrane. The results are compared with earlier reports.